Some random Friday afternoon brainstorming: could you print out bitcoins to function as user-created paper money?

QR code could be used to encode a transaction hash and a transaction signature on a piece of paper (along with a human-readable amount). A bitcoin client could print out coins that are in your wallet and marks them as "PRINTED" (so you don't accidentally spend them-- there would probably be a way of recovering them in case the paper versions were lost or stolen, and they'd automatically get removed when the paper versions were spent).

Give that piece of paper to a merchant connected to the Bitcoin network and they can scan it and transfer the coins into their wallet. They should then destroy the paper, because that transaction is spent.

Double-spending would be nearly impossible, because once you give the paper to the merchant you lose control over exactly when they submit it to the network to be verified.

The only problem I see is how the merchant gives you your change. The merchant could print out the change, but you'd have to trust that they were giving you valid, unspent coins, unless you have a device connected to the network that could verify them (but that's dumb, because if you do have such a device why bother with paper bitcoins?). We trust merchants not to give us counterfeit dollars... I wonder if fear of loss of reputation would be enough to keep them honest when giving paper bitcoins as change...

How often do you get the chance to work on a potentially world-changing project?

What you would want to do is act as a bitcoin reserve. You print paper money which promises to be redeemable for bitcoins by you. And you promise to keep those bitcoins reserved. If the person spending and accepting the paper money trust you, it would work fine.

Some random Friday afternoon brainstorming: could you print out bitcoins to function as user-created paper money?

QR code could be used to encode a transaction hash and a transaction signature on a piece of paper (along with a human-readable amount). A bitcoin client could print out coins that are in your wallet and marks them as "PRINTED" (so you don't accidentally spend them-- there would probably be a way of recovering them in case the paper versions were lost or stolen, and they'd automatically get removed when the paper versions were spent).

I see problems already.

First, there are no crypto-objects in your wallet that could actually be called coins. You could, at best, print out a 2d scancode that represents the signed transfer chain, but you would still need an address first. You would need some kind of bitcoin bank reserve willing to issue traditional banknotes or checks.

"The powers of financial capitalism had another far-reaching aim, nothing less than to create a world system of financial control in private hands able to dominate the political system of each country and the economy of the world as a whole. This system was to be controlled in a feudalist fashion by the central banks of the world acting in concert, by secret agreements arrived at in frequent meetings and conferences. The apex of the systems was to be the Bank for International Settlements in Basel, Switzerland, a private bank owned and controlled by the world's central banks which were themselves private corporations. Each central bank...sought to dominate its government by its ability to control Treasury loans, to manipulate foreign exchanges, to influence the level of economic activity in the country, and to influence cooperative politicians by subsequent economic rewards in the business world."

I only glanced at the check idea, so this might be the same thing, but you could theoretically send the amount of bitcoins that you want to spend to yourself and then write the private key on a piece of paper. Anyone who knows that private key can spend the money, so the check would need to be kept private. It would not be safe to let your cashier accept them since he or she could secretly steal them and say that they had already been spent.

in most casinos there is a printer in all the slot machines that print out what money you have left. there is a barcode on the piece of paper where u can put it into another slot machine or go to a casino teller and exchange it for cash. so I think such a concept is feasible since casinos already somewhat have such a system.

But I really think that using smartphones to make payments with bitcoin is a more comfortable way of doing things. Printing paper is a thing of the past.

My idea too, just type in the amount on your smartphone, type in the adress, cashier can see instantly the payment and done.I don't see why we need paper bitcoins and deal with al the troubles involved with it, printing, scanning, trust,... and it isn't eco friendly.

So I go for smartphone or maybe card, paper bitcoins doesn't have a future imho, but I can be wrong offcourse.

I remember reading about something like this almost twenty years ago in a Byte magazine article about electronic money. The concept at the time was in reference to "e-mailing" a debit transfer through a hash/cryptographic process which is in principle a concept similar to printing money on paper.

The trick here is to set up some system that would prevent a double spending of the money. Once that is solved, the rest is fairly mechanical and simple to accomplish.

I should note here that checks can and have been used as a medium of exchange in the past too, treated literally as a "bank note" in the same fashion that other more direct "bank notes" like most fiat currencies have been accepted. The reputation and trust of the individual who wrote the check was the deciding factor for acceptance of the check. Early Renaissance era merchants commonly used checks instead of currency for a great many transactions, and it was common for a check to go through the hands of hundreds of people before it finally landed at the bank for redemption. That is a bit more unusual today, where most checks usually get cashed out immediately, or a second generation at best. A noted exception would be for autograph hunters that may value the autograph more than the value of the check.

Here is a technical question on the topic: Is there a way to "spend" bitcoins to some hash address that could be verified as "available" (not recovered or claimed) and put both the private and public keys for claiming that money onto some piece of paper or to be transmitted through some lightweight protocol medium like e-mail, FTP, or even a simple thumb drive?

This is essentially setting up a "wallet" (in the Bitcoins sense) that would hold the value of the "money" being printed, where the wallet is backed up onto paper and you are in essence handing all of the information for that entire wallet over to some other person. They would then have the option of transferring all of the money in that wallet to their own wallet, or using that "money" in some way and handing it over to a 3rd person as a separate transaction. Once the money is transferred out of the wallet, the information about that wallet could then be discarded.

Am I missing something here, of would that work? It really would be the bitcoins equivalent to actual printed money, and for the paranoid you could easily verify that the coins really are in that wallet. A really paranoid merchant could "destroy" the wallet and re-issue the currency in fresh newly minted bitcoin certificates to their customers if they were making change... with the trust being strictly the integrity of the merchant alone and the relationship between the customer and the merchant.

Somebody being foolish (or stupid) and printing out multiple certificates with the same information would have their reputation tarnished when somebody tries to examine the contents of this wallet only to discover there is no value in there. Some might claim that the wallet was hacked, but the presumption would be that the person was trying to double-spend bitcoins.

I like this as it turns money back into a personal relationship experience. If you don't trust a stranger (or they are somebody who you know has scammed you in the past), you still can go back to the network to verify that the value of the money is real. But it can be a way to remove the electronic overhead for small value transactions on day to day purchases. Carrying around such a certificate would be no different than carrying around current government-issued money in a physical wallet.

My idea too, just type in the amount on your smartphone, type in the adress, cashier can see instantly the payment and done.I don't see why we need paper bitcoins and deal with al the troubles involved with it, printing, scanning, trust,... and it isn't eco friendly.

So I go for smartphone or maybe card, paper bitcoins doesn't have a future imho, but I can be wrong offcourse.

The problem with a smartphone or some other gadget is that there is overhead involved in trying to get the device to carry out the transaction. Yes, it could be done, but what happens when the networks are shut down temporarily, or you are in a situation where access to electronics is limited. Not everybody has 24/7 access to a network even in industrialized western nations.

I would also have to be convinced on the eco-friendly aspect of this too. You can print out quite a bit of paper for it to have the same environmental impact as the production of an iPhone. You are also burning up a fair bit of coal for simply operating that device, or causing other sorts of environmental damage.

Also, all trade of any kind is a matter of trust between the customer and the merchant. The question is how to reduce the threshold where distrust prevents a trade from happening. If you are in a situation where large numbers of Bitcoins (in terms of value) need to be transferred or if you really don't trust either the merchant or the customer, you would need something a bit more complex for the transfer. That is where cashier's checks and other more secure fiscal instruments are used even in today's business world.

If you have the smartphone, I would say go for it, but this idea of "paper bitcoins" and variations on the theme have a niche application where a smartphone isn't strictly needed. Dismissing completely out of hand the idea that you could make paper bitcoins doesn't really resolve the issue as to if it is is possible or practical.

The problem with a smartphone or some other gadget is that there is overhead involved in trying to get the device to carry out the transaction. Yes, it could be done, but what happens when the networks are shut down temporarily, or you are in a situation where access to electronics is limited. Not everybody has 24/7 access to a network even in industrialized western nations.

Well, a smartphone has mobile internet connection (almost) everywhere in a industrialized nation. Also, the shop could have a wifi or bluetooth connection to allow for the phone to connect and make the payment. And you dont need to have a bitcoin server in the phone, you could have a frontend that connects through ssh to you home bitcoin server and orders payments. You can even have the objects tagged with 3D barcodes that allows the phone to recoignaze them and the customer does not even have to type anything into the phone, just scan the barcodes with its phone and confirm the transaction.

Or this idea I just came up with: Imagine bitcoind would have a webpage frontend where you could order it to make payments (obviously password protected). The shop would only need to let you access your server webpage and make the payment.

Arent all this options simpler that printing paper?

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I would also have to be convinced on the eco-friendly aspect of this too. You can print out quite a bit of paper for it to have the same environmental impact as the production of an iPhone. You are also burning up a fair bit of coal for simply operating that device, or causing other sorts of environmental damage.

I dont think people is going to decide if they own an iPhone depending on its capability as a bitcoin wallet.

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Also, all trade of any kind is a matter of trust between the customer and the merchant. The question is how to reduce the threshold where distrust prevents a trade from happening. If you are in a situation where large numbers of Bitcoins (in terms of value) need to be transferred or if you really don't trust either the merchant or the customer, you would need something a bit more complex for the transfer. That is where cashier's checks and other more secure fiscal instruments are used even in today's business world.

If you want a middle man that the merchant could trust there alredy exists internet bitcoin accounts.

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If you have the smartphone, I would say go for it, but this idea of "paper bitcoins" and variations on the theme have a niche application where a smartphone isn't strictly needed. Dismissing completely out of hand the idea that you could make paper bitcoins doesn't really resolve the issue as to if it is is possible or practical.

Again, we'll see what happen. Maybe it does have some use, I just dont see it.

I think that Bitcoin has to add a new way to sign coins, something like "without-owner". ( a new sign in the protocol )

1) An user ( A ) ask the Bitcoin client to make a QR-code ( or a like ) of 100 Bitcoins ( it's an example )2) Bitcoin client cut 100 Bitcoins from the A user's wallet, and signs them ( 100 bitcoins ) with the new sign "without-owner", and generate the QR-Code of this operation.3) User B will be able to check the QR-Code to see if these 100 bitcoins ( he will also find that they are "100" bitcoins ) are still signed "without-owner" or not, and he can chose to own them or not.

The masses will demand paper, regardless of whether we consider it outdated or foolish. I think it's a good idea to have a redeemable note and/or check if we want Bitcoin to be available to them. How it should work I don't know.

No. Imagine if you have a kid mowing your lawn. In that case I think it would be much easier to hand him a bitcoin certificate for his work than trying to demand that he has bluetooth or a wireless device to receive the payment for services rendered.

The idea of a web front-end with password protection is even less secure (by a huge degree... and opening up the potential for that merchant to wipe out all of the money you now or in the near future will have) than simply handing over a cryptographically secure "wallet" or "wallets" with a predetermined and small amount of bitcoins of roughly the amount needed to conduct the transaction.

Mind you, this doesn't necessarily have to be done with physical objects. You could "e-mail" bitcoins in this manner to somebody who doesn't even have a Bitcoin node running, where they could even "redeem" the bitcoins for government-issued money straight away without even getting directly involved with Bitcoins. As an alternative, the bitcoins could simply be in a thumb drive instead where you could transfer over the files to the merchant representing the bitcoins you wish to use for the purchase, and they could even return the "change" to you in a similar fashion.

All in all, what you are suggesting here is far and away more complex than this paper currency system I'm suggesting here, and has been originally discussed at the start of this thread. This is a very lightweight bitcoin transfer system that has electronics of any kind as an optional aspect, and can enable purchases even if network access is unavailable on a temporary basis.

What keeps people honest here is that the values can be verified, and double spending is minimized through the verification process. Somebody who is double spending is committing fraud, which has existing legal implications. If they obtained those bitcoin certifications from a 3rd party, a legal investigation of fraud would then target that person who created those bogus bitcoin certificates in the first place.

Also, don't get caught up in the technical details. A 3-D bar code is there only to enable a higher density of information, not necessarily that it is superior to a 2-D or even 1-D (like a UPC symbol) bar code.

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I would also have to be convinced on the eco-friendly aspect of this too. You can print out quite a bit of paper for it to have the same environmental impact as the production of an iPhone. You are also burning up a fair bit of coal for simply operating that device, or causing other sorts of environmental damage.

I dont think people is going to decide if they own an iPhone depending on its capability as a bitcoin wallet.

That is handwaving off the idea. I'm just saying that the environmental friendly aspect is not nearly as clear-cut as was previously indicated and shouldn't be a rationale for dismissing this idea. It shouldn't even really play a part in this discussion, and to me is more of a wash in terms of potential environmental damage rather than a reason not to use this system.

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Also, all trade of any kind is a matter of trust between the customer and the merchant. The question is how to reduce the threshold where distrust prevents a trade from happening. If you are in a situation where large numbers of Bitcoins (in terms of value) need to be transferred or if you really don't trust either the merchant or the customer, you would need something a bit more complex for the transfer. That is where cashier's checks and other more secure fiscal instruments are used even in today's business world.

If you want a middle man that the merchant could trust there alredy exists internet bitcoin accounts.

This is more than just a middle man, and this system doesn't require a 3rd party to be involved in the first place. You create the "bitcoin certificate" from BTC you already have, and present that to a merchant or whomever you need to pay in terms of services or products rendered. The purpose here is to provide a very simple and technologically lightweight system for payments using bitcoins.

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If you have the smartphone, I would say go for it, but this idea of "paper bitcoins" and variations on the theme have a niche application where a smartphone isn't strictly needed. Dismissing completely out of hand the idea that you could make paper bitcoins doesn't really resolve the issue as to if it is is possible or practical.

Again, we'll see what happen. Maybe it does have some use, I just dont see it.

For you, I think this would take a very direct and physical demonstration of the concept to convince you that it could work. It would never be something that I would be comfortable in terms of a purchase of an automobile or a house, but if I went to a local farmer's market and handed over a 5 BTC note to buy a bag of apples, that would be an almost ideal application of this "technology".

As I also hinted at above, this would also be a way to expand the number of Bitcoin users in a rather substantive way where they wouldn't necessarily have to be generating coins to join into the network, or even have a need to generate the coins. A bitcoin certificate would be a great way to advertise the project at say a convention or a conference, where you could "give away" bitcoins for people to try out the system.... sort of like how the bitcoin faucet currently works but on a larger scale.

The masses will demand paper, regardless of whether we consider it outdated or foolish. I think it's a good idea to have a redeemable note and/or check if we want Bitcoin to be available to them. How it should work I don't know.

I talked about something called "wallet escrow" on this thread awhile back:

I think the concept could be applied here in terms of a "throw away" wallet too, where the information would be stored and encrypted in a strong fashion. My original intent here was to provide a safe way for backing up wallet information so if your computer crashed you could recover the information quickly and it wouldn't even necessarily require anything more than the *very strong* password to recover the information. I'm thinking a SHA2-512 bit hash or similar kind of high difficulty password, not your run of the mill ordinary passwords here.

In theory you could also "print" your "main" wallet in this fashion too, as a certificate for back-up purposes, and keep that certificate locked in a safe or a bank safety deposit box. If your local node crashed, all you would need to restore the wallet is to get that hash key. The hash key would be printed on this certificate in a fashion like serial numbers are used on government-issued currency.

Printing out a certificate where you even print out the quantity of money in that wallet in clear distinguishable letters (40 point bold type or larger) would be basically all that would be needed to get this to work.

This is a very interesting idea. The more I read about it, the better it sounds. As RHorning has said, implementing this would give a huge boost to "outside" people and let them know about the project. Using a "wallet escrow" system would make this as secure as normal wallets and prohibit double spending just as we do now. Very nice idea!

The ability to use simple "BitCoin notes" just like everyday paper currency has HUGE advantages for building the system and ease of access for even small business. I would assume that eventually bitcoin will be allowed to use with automated checkout systems IRL like at grocery stores etc. Until then, this definitely gets your foot in the door to those willing to accept it.

Coupling this with an "elevator pitch" would build recognition and acceptance very quickly.

No. Imagine if you have a kid mowing your lawn. In that case I think it would be much easier to hand him a bitcoin certificate for his work than trying to demand that he has bluetooth or a wireless device to receive the payment for services rendered.

Why wont you use the mobile internet connection or the internet connection of your house? Why does the kid mowing your lawn need to provide a internet connection?

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Mind you, this doesn't necessarily have to be done with physical objects. You could "e-mail" bitcoins in this manner to somebody who doesn't even have a Bitcoin node running, where they could even "redeem" the bitcoins for government-issued money straight away without even getting directly involved with Bitcoins.

This is not very interesting as it drives people away from bitcoins.

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As an alternative, the bitcoins could simply be in a thumb drive instead where you could transfer over the files to the merchant representing the bitcoins you wish to use for the purchase, and they could even return the "change" to you in a similar fashion.

This is a good idea, but involves merchant computer use, and it seems similar to me to the smartphone solutions I already mention. The pros of this option is that it seems slightly simpler as the bitcoin program could have a transfer option to a usb wallet (or to a smartphone wallet for the case, they have usb connections). The cons of this option is that you can only access the funds you transfered to the usb dongle (or the smartphone memory).

This seems to me like a smartphone solution, not a paper solution.

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All in all, what you are suggesting here is far and away more complex than this paper currency system I'm suggesting here, and has been originally discussed at the start of this thread. This is a very lightweight bitcoin transfer system that has electronics of any kind as an optional aspect, and can enable purchases even if network access is unavailable on a temporary basis.

I dont think installing a frontend or a wallet for bitcoin in the mobile phone from a app shop is complicated.

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What keeps people honest here is that the values can be verified, and double spending is minimized through the verification process. Somebody who is double spending is committing fraud, which has existing legal implications. If they obtained those bitcoin certifications from a 3rd party, a legal investigation of fraud would then target that person who created those bogus bitcoin certificates in the first place.

How does the kid that mows the lawn know that the certificate is valid? To really be able to verify the certificate you need a computer, and then the smartphone solution its more practical.

I think that a bitcoin wallet software for mobile phones or usb dongles is more practical, if you dont want to have your phone connected to the internet in any way, than this paper certificates. If this paper would be used without imediate validation in the bitcoin network, they could be unreliable and give bad image to bitcoin currency.

It all comes down to how much you trust the entitiy you are transacting with.

If I'm paying the kid mowing my lawn in Bitcoin 'notes' I know I'm honest. If there is some problem we can sort it out when he comes back next month.If I'm buying my groceries from 'Big Grocery Store' (BGS) they will be doing online transaction processing to verify my Bitcoin notes are valid before I leave the store, and I can trust that the notes they are printing me for my change will be valid.If I'm borrowing 10BTC from my friend, he can pass a note from the BGS to me because I can trust he he's not double spending it. The note can proceed down the chain of trust.

If I'm buying a DVD from a guy on a street corner, he might not be inclined to take my bitcoin note (unless he has an iPhone to check the transaction is valid) and I'll probably want to use exact change, because I'm not going to trust any notes he gives me in return.

Bitcoin notes are a great solution when you are:

a) Offlineb) Dealing with someone you trust.

It also doesn't prevent you choosing to use some other method.It just provides you with an extra option. Which is a Good Thing.

[No. Imagine if you have a kid mowing your lawn. In that case I think it would be much easier to hand him a bitcoin certificate for his work than trying to demand that he has bluetooth or a wireless device to receive the payment for services rendered.

It's not required that the kid have a bluetooth phone, although he is likely to already have one. It's not even required that *you* have one, although that might make the transfer more convientent. All that is required is that you have an address of his. He doesn't need to verify that your money is good; he knows where you live and he couldn't force you to pay him if you refused anyway. He is dependent upon your honesty from the start, although if you screw him, not only are you going to have to cut your own grass, you might wake up one day and find someone has salted your flowers.

"The powers of financial capitalism had another far-reaching aim, nothing less than to create a world system of financial control in private hands able to dominate the political system of each country and the economy of the world as a whole. This system was to be controlled in a feudalist fashion by the central banks of the world acting in concert, by secret agreements arrived at in frequent meetings and conferences. The apex of the systems was to be the Bank for International Settlements in Basel, Switzerland, a private bank owned and controlled by the world's central banks which were themselves private corporations. Each central bank...sought to dominate its government by its ability to control Treasury loans, to manipulate foreign exchanges, to influence the level of economic activity in the country, and to influence cooperative politicians by subsequent economic rewards in the business world."

He doesn't need to verify that your money is good; he knows where you live and he couldn't force you to pay him if you refused anyway. He is dependent upon your honesty from the start, although if you screw him, not only are you going to have to cut your own grass, you might wake up one day and find someone has salted your flowers.